﻿#region using 

using System;
using System.Diagnostics;
using System.Runtime.InteropServices;
using System.Windows.Forms;

#endregion

namespace Utils.Hook
{
    public class KeyboardHook
    {
        public delegate int HookProc(int nCode, int wParam, IntPtr lParam);

        #region ddlimport

        //使用此功能，安装了一个钩子
        [DllImport("user32.dll", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
        public static extern int SetWindowsHookEx(int idHook, HookProc lpfn, IntPtr hInstance, int threadId);

        //调用此函数卸载钩子
        [DllImport("user32.dll", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
        public static extern bool UnhookWindowsHookEx(int idHook);

        //使用此功能，通过信息钩子继续下一个钩子
        [DllImport("user32.dll", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
        public static extern int CallNextHookEx(int idHook, int nCode, int wParam, IntPtr lParam);

        //使用WINDOWS API函数代替获取当前实例的函数,防止钩子失效
        [DllImport("kernel32.dll")]
        public static extern IntPtr GetModuleHandle(string name);

        /// <summary>
        ///     ToAscii职能的转换指定的虚拟键码和键盘状态的相应字符或字符
        /// </summary>
        /// <param name="uVirtKey">[in] 指定虚拟关键代码进行翻译。 </param>
        /// <param name="uScanCode">[in] 指定的硬件扫描码的关键须翻译成英文。高阶位的这个值设定的关键，如果是（不压）</param>
        /// <param name="lpbKeyState">
        ///     [in]
        ///     指针，以256字节数组，包含当前键盘的状态。每个元素（字节）的数组包含状态的一个关键。如果高阶位的字节是一套，关键是下跌（按下）。在低比特，如果设置表明，关键是对切换。在此功能，只有肘位的CAPS
        ///     LOCK键是相关的。在切换状态的NUM个锁和滚动锁定键被忽略。
        /// </param>
        /// <param name="lpwTransKey">[out] 指针的缓冲区收到翻译字符或字符。 </param>
        /// <param name="fuState">
        ///     [in] Specifies whether a menu is active. This parameter must be 1 if a menu is active, or 0
        ///     otherwise.
        /// </param>
        /// <returns></returns>
        [DllImport("user32")]
        public static extern int ToAscii(int uVirtKey, int uScanCode, byte[] lpbKeyState, byte[] lpwTransKey, int fuState);

        //获取按键的状态
        [DllImport("user32")]
        public static extern int GetKeyboardState(byte[] pbKeyState);

        //[DllImport("user32.dll", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
        //private static extern short GetKeyState(int vKey);

        #endregion;

        private const int WM_KEYDOWN = 0x100; //KEYDOWN 
        private const int WM_KEYUP = 0x101; //KEYUP
        private const int WM_SYSKEYDOWN = 0x104; //SYSKEYDOWN
        private const int WM_SYSKEYUP = 0x105; //SYSKEYUP
        private HookProc KeyboardHookProcedure; //声明KeyboardHookProcedure作为HookProc类型

        public event KeyEventHandler KeyDownEvent;
        public event KeyEventHandler KeyUpEvent;
        public event KeyPressEventHandler KeyPressEvent;

        private static int hKeyboardHook; //声明键盘钩子处理的初始值
        //值在Microsoft SDK的Winuser.h里查询
        public const int WH_KEYBOARD_LL = 13; //线程键盘钩子监听鼠标消息设为2，全局键盘监听鼠标消息设为13

        public void Install()
        {
            // 安装键盘钩子
            if (hKeyboardHook != 0) return;

            KeyboardHookProcedure = KeyboardHookProc;
            hKeyboardHook = SetWindowsHookEx(WH_KEYBOARD_LL, KeyboardHookProcedure, GetModuleHandle(Process.GetCurrentProcess().MainModule.ModuleName), 0);
            //hKeyboardHook = SetWindowsHookEx(WH_KEYBOARD_LL, KeyboardHookProcedure, Marshal.GetHINSTANCE(Assembly.GetExecutingAssembly().GetModules()[0]), 0);
            //************************************ 
            //键盘线程钩子 
            //SetWindowsHookEx( 2,KeyboardHookProcedure, IntPtr.Zero, GetCurrentThreadId());//指定要监听的线程idGetCurrentThreadId(),
            //键盘全局钩子,需要引用空间(using System.Reflection;) 
            //SetWindowsHookEx( 13,MouseHookProcedure,Marshal.GetHINSTANCE(Assembly.GetExecutingAssembly().GetModules()[0]),0); 
            // 
            //关于SetWindowsHookEx (int idHook, HookProc lpfn, IntPtr hInstance, int threadId)函数将钩子加入到钩子链表中，说明一下四个参数： 
            //idHook 钩子类型，即确定钩子监听何种消息，上面的代码中设为2，即监听键盘消息并且是线程钩子，如果是全局钩子监听键盘消息应设为13， 
            //线程钩子监听鼠标消息设为7，全局钩子监听鼠标消息设为14。lpfn 钩子子程的地址指针。如果dwThreadId参数为0 或是一个由别的进程创建的 
            //线程的标识，lpfn必须指向DLL中的钩子子程。 除此以外，lpfn可以指向当前进程的一段钩子子程代码。钩子函数的入口地址，当钩子钩到任何 
            //消息后便调用这个函数。hInstance应用程序实例的句柄。标识包含lpfn所指的子程的DLL。如果threadId 标识当前进程创建的一个线程，而且子 
            //程代码位于当前进程，hInstance必须为NULL。可以很简单的设定其为本应用程序的实例句柄。threaded 与安装的钩子子程相关联的线程的标识符
            //如果为0，钩子子程与所有的线程关联，即为全局钩子
            //************************************ 
            //如果SetWindowsHookEx失败
            if (hKeyboardHook != 0) return;

            Uninstall();
            throw new Exception("安装键盘钩子失败");
        }

        public void Uninstall()
        {
            bool retKeyboard = true;

            if (hKeyboardHook != 0)
            {
                retKeyboard = UnhookWindowsHookEx(hKeyboardHook);
                hKeyboardHook = 0;
            }

            if (!retKeyboard) throw new Exception("卸载钩子失败！");
        }

        private int KeyboardHookProc(int nCode, int wParam, IntPtr lParam)
        {
            if ((nCode < 0) || (KeyDownEvent == null && KeyUpEvent == null && KeyPressEvent == null)) return CallNextHookEx(hKeyboardHook, nCode, wParam, lParam);

            KeyboardHookStruct myKeyboardHookStruct = (KeyboardHookStruct)Marshal.PtrToStructure(lParam, typeof (KeyboardHookStruct));
            
            if (KeyDownEvent != null && (wParam == WM_KEYDOWN || wParam == WM_SYSKEYDOWN))
            {
                Keys keyData = (Keys)myKeyboardHookStruct.vkCode;
                KeyEventArgs e = new KeyEventArgs(keyData);
                KeyDownEvent(this, e);
            }

            if (KeyPressEvent != null && wParam == WM_KEYDOWN)
            {
                byte[] keyState = new byte[256];
                GetKeyboardState(keyState);

                byte[] inBuffer = new byte[2];
                if (ToAscii(myKeyboardHookStruct.vkCode, myKeyboardHookStruct.scanCode, keyState, inBuffer, myKeyboardHookStruct.flags) == 1)
                {
                    KeyPressEventArgs e = new KeyPressEventArgs((char)inBuffer[0]);
                    KeyPressEvent(this, e);
                }
            }

            if (KeyUpEvent == null || (wParam != WM_KEYUP && wParam != WM_SYSKEYUP)) return CallNextHookEx(hKeyboardHook, nCode, wParam, lParam);
            {
                Keys keyData = (Keys)myKeyboardHookStruct.vkCode;
                KeyEventArgs e = new KeyEventArgs(keyData);
                KeyUpEvent(this, e);
            }

            return CallNextHookEx(hKeyboardHook, nCode, wParam, lParam);
        }

        ~KeyboardHook()
        {
            Uninstall();
        }
    }
}
